28. Legion of Superheroes vs. The Forces of Darkseid
The Great Darkness Saga involved the Legion of Super-Heroes fighting against some dark beings serving their dark master.
The Legion eventually learns that the dark beings are reverse-clones of powerful beings of the 20th Century like Superman and a Guardian of the Universe.
There is also a mysterious young boy who is being targeted by the dark beings. The Legion protects the boy and fights against the dark beings.
Mon-El confronts the dark master, who has already defeated Mordru and the Time Trapper and taken power from them (so he’s REALLY powerful right now) and the dark master hits him so hard he goes into a coma.
Mon-El recognized the dark master from his time in the 20th Century, but he was knocked unconscious before he could warn the rest of the Legion. Seeing the Daxamite Mon-El, the dark master is hit with an idea. The dark master travels to Daxam where he uses his power to turn the Daxamites into thralls of his power and also takes them to a yellow sun where they are now all Supermen.
Now that he is on the precipice of conquering the universe, we learn that the dark master is Darkseid!
The Legion has its hands full fighting against the brainwashed Daxamites (but Element Lad helps by adding some lead to the game).
Ultimately, though, it is the young boy who saves the day, as it turns out to be Highfather, Darkseid’s opposite.
Highfather is not powerful enough now to stop Darkseid himself, but through a series of machinations, lets loose the populace of Daxam (now free of Darkseid’s control and none too pleased with Darkseid) on Darkseid, forcing him to retreat from his plans of universe domination.
That’s just a VERY brief description - there are a LOT more twists and turns than that - this Paul Levitz and Keith Giffen storyline was so good that it was hard for them ever to meet this level of quality again, although they sure tried!